Calendar Roller End Induction Heating Against Thermal Crowning

The patent applies induction heating coils specifically at the end portions of the calendar roller rather than uniform heating across the entire roller surface. This localized heating approach creates a temperature gradient that compensates for thermal crowning, maintaining uniform roller diameter and resulting in consistent material layer thickness across the substrate width.

The patent utilizes controlled thermal expansion of the roller end portions through induction heating. By heating the ends of the roller, the material expands locally to compensate for the natural thermal crowning effect, thereby maintaining a uniform roller diameter profile and ensuring even material distribution during the calendaring process.

The patent implements localized induction heating coils at the roller end portions where heat loss is greatest. This targeted approach provides additional heating precisely where needed, compensating for the higher heat loss at the ends without requiring increased heating across the entire roller surface, thus maintaining overall temperature consistency while addressing end portion heat loss.

The patent applies preliminary heating to the roller end portions before the calendaring process begins and maintains this heating during operation. This preliminary anti-action counteracts the inevitable heat loss at the roller ends, preventing thermal crowning from developing and maintaining uniform temperature distribution across the roller surface.